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A- level biology - 3.3 organisms exchange substances with their environment > the circulatory system > Flashcards

the circulatory system Flashcards

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1
Q

what do mammals have to transport materials around the body ?

A

a dedicated mass transport system

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2
Q

why do mammals require a dedicated mass transport system?

A

due to their low SA:VOL ratio

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3
Q

what is the dedicated mass transport system in mammals referred to as ?

A

the circulatory system

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4
Q

what does the circulatory system consist of ?

A

the heart and associated blood vessels

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5
Q

what are some examples of blood vessels ? (4)

A
  • arteries
  • arterioles
  • veins
  • capillaries
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6
Q

what kind of mass transport system do most mammals have ?

A

a double circuit mass transport system

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7
Q

which various substances are transported in the blood ? (4)

A
  • respiratory gases like oxygen and carbon dioxide
  • the products of digestion such as glucose and amino acids
  • metabolic waste such as urea
  • hormones such as adrenaline and insulin
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8
Q

what are the names of the 2 circuits in the double circuit circulatory system ?

A
  • pulmonary circuit
  • systematic circuit
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9
Q

what is the role of the pulmonary system ?

A

the pulmonary circuit carries blood from the heart to the lungs and then back to the heart

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10
Q

what is the role of the systematic circuit ?

A

the systematic circuit carries blood around the rest of the body

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11
Q

how is the heart supplied with blood?

A

the heart has its own blood supply
- the left and right coronary arteries supply the heart with blood

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12
Q

what is the role of the arteries ?

A

arteries carry blood away from the heart

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13
Q

what are the features of arteries ? and what does it help with ?

A

arteries have thick elastic walls that recoil when the heart beats
- it helps maintain high pressure
they have folded endothelium
- which allows the artery to stretch

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14
Q

what d the arteries mostly carry ?

A

arteries mostly carry oxygenated blood around the body

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15
Q

what does the pulmonary artery carry ?

A

the pulmonary artery carries deoxygenated blood from the heart to the lungs

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16
Q

what do arteries branch into ?

A

arteries branch into smaller vessels called arterioles

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17
Q

what are the features of arterioles ?

A
  • arterioles form a network of vessels around the body
  • arterioles can constrict or dilate depending on the body’s demand for blood
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18
Q

2 features of arteries from diagram ?

A
  • have thick muscular walls to tolerate high pressure
  • narrow lumen
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19
Q

what is the role of veins ?

A

veins carry blood towards the heart

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20
Q

what are the differences between veins and arteries ?

A
  • veins function at a lower pressure than arteries
  • veins have a wider lumen than arteries
  • they have very little elastic tissue
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21
Q

what do veins contain ? and what are its function ?

A

veins contain valves
- valves prevent the backflow of blood

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22
Q

what do muscles do to aid blood flow in the veins ?

A

muscles contract

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23
Q

what do veins mostly carry ?

A

deoxygenated blood around the body

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24
Q

what is the role of the pulmonary vein ?

A

the pulmonary vein carries oxygenated blood from the lungs to the heart

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25
Q

what do arterioles branch into ?

A

capillaries

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26
Q

what are capillaries ?

A

the smallest blood vessels

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27
Q

how thick are the capillary walls ?

A

1 cell thick

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28
Q

what is exchanged at blood vessels ?

A

compounds

29
Q

what diffuses into cells from the capillaries ?

A

glucose and oxygen

30
Q

what is the benefit for having a huge number of capillaries

A

because it increases the surface area for gas exchange - link to fix law

31
Q

what is meant by capillary beds ?

A

capillary beds are capillary networks that are located in tissues

32
Q

how wide are the capillary endothelium ?

A

the capillary endothelium are only wide enough for a single red blood cell to squeeze through at a time

33
Q

where is tissue fluid located ?

A

tissue fluid surrounds cells in tissue

34
Q

what is tissue fluid made out of ?

A

tissue fluid is made from the molecules that leave the plasma

35
Q

what molecules enter the tissue fluid ?

A

oxygen
water
digested nutrients

36
Q

what molecules remain in the bloodstream and not go into the tissue fluid ?

A

red blood cells and larger proteins

37
Q

which molecules are removed from the tissue fluid by cells ?

A

oxygen and nutrients

38
Q

what molecules are released into the tissue fluid ?

A

metabolic waste like urea

39
Q

what happens at capillary beds ?

A

the exchange of materials

40
Q

what does high hydrostatic pressure at the arteriole end cause ?

A

high hydrostatic pressure at the arteriole end forces fluid out of the blood and into the surrounding tissue

41
Q

what will happen to some water when there is high hydrostatic pressure ?

A

some water returns a the venous end due to the differences in water potential

42
Q

what will happen to excess tissue fluid ?

A

excess tissue fluid will drain into the lymphatic system

43
Q

what is the definition of the heart ?

A

the heart is a muscular organ that pumps blood around the body

44
Q

how many chambers does the heart have ?

A

4

45
Q

what is found at the top of the heart ?

A

the left and right atria

46
Q

what is found at the bottom of the heart ?

A

the left and right ventricles

47
Q

how is the heart adapted to its function ?

A
  • the ventricles are thicker than the atria
  • the left ventricle has a thick wall of muscle
  • the heart has valves to prevent the backflow of blood
48
Q

why are the ventricles thicker than the atria ?

A

because the ventricles have to pump blood to the body whereas the atria only have to pump blood to the ventricles

49
Q

why does the left ventricle have a thick wall of muscle ?

A

because it allows the ventricle to contract powerfully to pump blood around the body

50
Q

what is the function of atrioventricular valves ? (AV valves )

A

the atrioventricular valves link the atria to the ventricles

51
Q

what is the function of the semi-lunar valves (SL valves) ?

A

the semi-lunar valves link the ventricles to the pulmonary artery and the aorta

52
Q

in what direction do valves open ?

A

valves only open in 1 direction

53
Q

what does whether or not the valve open depends on ?

A

whether or not the valve is open depends on the pressure of the heart chambers

54
Q

what happens to a valve if the pressure if higher behind the valve ?

A

the valve is forced open

55
Q

what happens to a valve if the pressure is higher in front of the valve ?

A

the valve is closed shut

56
Q

what does the link between pressure of the chambers and the opening and closing of the valve ensure ?

A

it ensures that the flow of blood is undirectional

57
Q

what does maintaining the blood flow as undirectional ensure ?

A

using this mechanism ensures blood does not flow the wrong way around the heart

58
Q

what is meant by the cardiac cycle ?

A

the cardiac cycle is the sequence of contraction and relaxation in the heart
- it is how blood is continually circulated around the body

59
Q

how many stages are there in the cardiac cycle?

A

3

60
Q

what happens in atrial systole ?

A

a) during atrial systole , the ventricles are relaxed. the atria contract, increasing the pressure in the atrial chambers
b) the AV valves open and blood is forced into the ventricles
c) as the ventricles receive this blood, the pressure increases slightly

61
Q

what happens in ventricular systole ?

A

a) the atria now relax and the ventricles contract . this increases the pressure of the ventricular chambers
b) the pressure in the ventricles is higher than the pressure in the atria so the AV valves close
c) the pressure in the ventricles opens the SL valves and blood is forced out of the pulmonary artery and the aorta

62
Q

what happens in diastole ?

A

a) both the atria and ventricles relax. The SL valves close due to the higher pressure in the vessels. Blood returns tot he heart and the atria begin to fill with blood again This increases the pressure of the atria slightly
b) the higher pressure in the atria forces the AV valves to open and some blood flows passively from atria to ventricles

63
Q

state the different ways to measure the activity of the heart ?

A
  • atrial pressure
  • ventricular pressure
  • ventricular volume
  • electrocardiogram
  • phonocardiogram
64
Q

what are the 2 main measures of cardiac activity ?

A
  • heart rate
  • stroke volume
65
Q

what is the definition of heart rate ?

A

the number of times the heart beats in 1 minute (bpm)

66
Q

what is the definition of stroke volume ?

A

the average volume of blood pumped during each heartbeat (cm3)

67
Q

what is the calculation for cardiac output ?

A

cardiac output (cm3min-1) = heart rate (bpm) x stroke volume (cm3)

CO = HR x SV

68
Q

what is meant by cardiac output ?

A

cardiac output is the total volume of blood pumped out by the heart in 1 minute (cm3 min-1)

69
Q

what kind of people are likely to have hearts with a high cardiac output ?

A

those who regularly practice excercise

A- level biology - 3.3 organisms exchange substances with their environment (11 decks)

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